A "migration and development" policy is difficult to define.
Success might be difficult to define, but it's easy to see.
It is, however, more difficult to define such words.
The biblical concept of "glory" is difficult to define.
It is difficult to define the boundaries of art-if not impossible.
The boundaries between therapy and enhancement can be difficult to define.
This makes it difficult to define them by comparing their morphology.
Esto hace que sea difícil de definir, por comparación de su morfología.
Human or personal authenticity is difficult to define, attain or measure.
La autenticidad humana o personal es difícil de definir, obtener o medir.
I know our relationship has always been... difficult to define.
Sé que nuestra relación siempre ha sido... difícil de definir.
The unframed software art is a bit more difficult to define and control.
El unframed software art es un poco más difícil de definir y controlar.
Today it is difficult to define how far this genre covers.
Hoy en día es difícil definir hasta dónde abarca este género musical.
Still, it is difficult to define what they do.
Aun así, resulta difícil de definir lo que hacen.
The photograph developed hazily, leaving their smiles soft and difficult to define.
La fotografía se reveló vagamente, dejando sus sonrisas suaves y difíciles de definir.